What is alloy 825 pipe made of?
Alloy 825 is a nickel-chromium-iron solid solution strengthened alloy with a nominal chemical composition of 42% nickel, 21% chromium, and 22% iron, with additions of molybdenum, titanium, and copper. It is commonly referred to by the trade name Incoloy 825 and the generic name UNS N08825.
Features
Corrosion Resistance
With a PREN of 31 and a high nickel content of 42%, 825 alloy has good corrosion resistance in many environments, including reducing and oxidizing acids, organic acids, seawater, salts, and alkalis. It is particularly resistant to sulfuric and phosphoric acids. The addition of molybdenum gives 825 alloy good resistance to chloride-induced localized corrosion, including pitting, crevice corrosion, and stress corrosion cracking. In addition, 825 alloy has good oxidation resistance.
Service Temperature
825 alloy has service temperatures from cryogenic to 1000°F (540°C). It is not recommended to use 825 alloy at temperatures above 1000°F (538°C) because deleterious phases will form, negatively affecting impact toughness and ductility.
Mechanical Properties
825 alloy is available in the annealed condition or it can be strengthened by the pilger process. Alloy 825 retains useful mechanical properties up to about 1000°F (538°C) and has good toughness at cryogenic temperatures.
